It was the nightmare scenario for Sir Dave Brailsford, Chris Froome and Team Sky: a succession of crashes that eliminated the defending Tour de France champion en route to Arenberg over the cobbles of the Hell of the North. As is so often the case when the Tour travels over the pavé, the issue was not so much riding over the cobbles, but getting to them, and this time round the crazy fight to reach the pavé first was made still more dangerous by sodden roads.

The consequences of Froome’s withdrawal for Sky were seen on the penultimate section of pavé between Wandignies-Hamage and Hornaing, 13km from the finish, when Geraint Thomas and Richie Porte attacked from what remained of the peloton – if such a term could be applied to the bedraggled group gathered around Alberto Contador – to move forward to another group led by the Garmin domestiques and their leader, Andrew Talansky.

From that group, Porte and Thomas attacked again on the final section of cobbles to put more time between themselves and Contador. It was a classic piece of defensive riding, as at the end of a stage such as this – full on, run off at a 47kph average in horrendously wet conditions – most riders will weaken towards the end and those with anything left in their legs have no option but to move forwards. The late push meant Porte ended the stage in eighth and Thomas in 14th overall.

Porte had been designated Sky’s replacement leader for the stage in the event that anything should happen to Froome, and, given that the defending champion started out with his wrists heavily strapped from his crash the afternoon before, there was every chance that it would. Porte will continue as the British team’s No1 for the rest of the race. The situation Sky find themselves in now is similar to their plight after Sir Bradley Wiggins crashed out in 2011: they are scrabbling for what they can get, rather than in control as they were in 2012 and 2013.

Neither man offers anything similar to Froome or Wiggins, or the Norwegian Edvald Boasson Hagen – who snaffled two stage wins to salvage Sky’s Tour after Wiggins departed in 2011 – but they will at least provide Sky with a focus for the overall standings. Porte was, after all, intended to be the team’s leader for the Giro d’Italia this year, while there has been speculation for several years that Thomas’s all-round ability, massive engine and tough mentality might make him a possible overall contender for the Tour in the style of Wiggins.

Both riders have pasts that suggest they can step up in the Tour. Porte showed his potential in the 2010 Giro d’Italia when he finished seventh overall, leading the race for three stages. He won Paris-Nice in 2013, and finished second overall to Nairo Quintana in the Tour of the Basque Country. All promising enough. Thomas, for his part, has twice won the Bayern Rundfahrt – not in Porte’s league – but finished 15th in the Critérium du Dauphiné in 2013 while on team duty for Froome. In 2011, he was seen climbing strongly on the final Alpine stage of the Tour, and last year he told the Guardian that long-term he wanted to target the major Tours after losing several kilos as Wiggins did. Clearly, neither man’s true ability will be known until the opening is there for them.

Froome’s unfortunate departure is bound to raise questions about Brailsford’s controversial decision to omit Wiggins in order to enable Sky to focus exclusively on the Kenyan-born 2013 Tour winner. The performance logic of excluding Wiggins and giving Froome an unhindered run, without the pressure and potential stresses of having the 2012 winner in the team, looked impeccable, but the wisdom or otherwise of Brailsford’s decision will remain hotly discussed, the more so now that Froome has lost a second major stage race this year – after the Dauphiné – owing to crashes.

Wiggins’s proven ability on the pavé would probably have stood him in good stead into Arenberg. Questions have been asked about his ability to perform in the rain but, when he is on song and there is a purpose to it, Wiggins is perfectly willing and able to race hard in wet conditions. He reckoned that after winning the Tour of California in May he was on course to achieve similar form to when he won the Tour in 2012, suggesting that he might have pushed for a high place overall had he been given the chance.

That really is pure conjecture but what is certain is that Wiggins no longer represents the future, for Sky, no matter what he may represent for British cycling and British fans.

He may have one or two good Grand Tours left in him – the Vuelta this autumn might offer some indication of that – but at 29 and 28 respectively, Porte and Thomas might well be a better investment for the medium if not the long term. Brailsford needs to know precisely how they will perform when given their opportunity on the big stage, and Wednesday’s unfortunate events will at least make that possible.